Subaru is creeping up on a big birthday because, by my reckoning, the Impreza WRX is about to turn 10.

Well, it will at the end of this year anyway, and in February 2004 it will be a decade since the compact, all-wheel-drive turbo rocket landed on Australian shores. Given the marketing clout of car companies, it would be rare indeed for the occasion to go unnoticed.

In that relatively brief period the WRX has become a cult car -- giving middle-aged drivers the chance to feel younger, people of lesser years an opportunity to emulate their rally gods -- and terrorised the chiefs of domestic car companies whose gas-guzzling V8 muscle cars couldn't keep up with the turbo tearaway.

On the social side it has made the front page of newspapers as a favourite of joy riders and ram raiders while giving insurance companies the odd headache. Oh yes, it has taken out numerous rally titles as a competition car as well.

Late last year Subaru gave the second-generation WRX and its less illustrious Impreza stablemates an overhaul, changing front and rear sheet metal and lights for a totally different look from the original, a controversial bug-eyed styling, and introduced engine changes to improve the WRX's driveability and performance.

Then, just as 2002 was coming to a close, it also slipped in the new version of the WRX STi. As before, this is an even hotter and dearer version of Subaru's performance flagship, with go-faster bits bolted on by performance division Subaru Tecnica International in much the same way HSV modifies Holden Commodores.

It is a wild-looking car. On top of the WRX's already fat wheels, side skirts and bumper extensions goes a huge wing, and an even bigger version of the bonnet scoop feeds the engine's intercooler under the bonnet. There are also fog-lamp covers in lieu of the lights themselves (it's a weight-saving measure), the trademark pink STi badges and a number of interior trim items such as a smaller three-spoke steering wheel and unique instrument panel.

What hasn't changed is the uprated version of the WRX's 2.0-litre, horizontally opposed turbo engine with variable valve timing. In the STi it puts out 195kW of power or 27kW more than the WRX, and torque jumps by 43Nm to 343Nm at 4000rpm, which is 400rpm higher in the rev range.

The result is scintillating performance, especially as the six-speed manual gearbox offers a tightly grouped bunch of ratios for maximum acceleration and the all-wheel-drive system means not a jot of engine power is wasted in wheelspin. There's a light and a beeper that tell you when to change gears (it's adjustable depending on what revs are needed) and even a sprayer that squirts water on the turbo's intercooler (basically another radiator to cool the air intake temperature) for a little extra power.

Pushed through all the gears the relatively light, 1470-kilogram STi leaves all but highly priced sports cars in its wake as it reputedly hits 100kmh from standstill in 5.5 seconds.

While it might be tempting to drive like that, the fact is more time is spent tooling around the suburbs and here the STi is less happy. While there's plenty of engine power high in the rev range, anywhere below about 4000rpm there's not much urge at all.

The turbo takes a while to produce boost and it is frustrating to have that sort of lag in situations as common as a second-gear left turn in traffic. It's a similar situation on the open road, where a degree of planning -- either getting on the throttle early or shifting back a gear or two -- is needed for overtaking.

It isn't a minor glitch but a major shortcoming of the car. The standard WRX has much more bottom-end urge and is far more enjoyable to drive most of the time.

But few cars are more exhilarating on tight twisty roads. The STi gets front and rear limited-slip differentials and substantially stiffer suspension than the WRX, and it shows in absolute grip on the road, almost no body roll and an ability to dart through corners and, if the engine is on the boil, move out of them safely and swiftly. The huge Brembo brakes haul it down time and again with no sign of fade.

The payback comes in a fairly rigid ride that finds every imperfection in the road surface, and makes quite an amount of crashing and banging as it does. This is no refined, silent tourer, but a four-door sports car that means business, and it shows.

Inside there's lots of lurid blue carpet, a chunky little three-spoke wheel and a perfect driving position helped by wrap-around rally-style seats for the fighter-pilot level of cornering G-forces. Because it is a four-door sedan (the five-door body style isn't offered in STi trim) there's room for a couple of adults in the rear and their luggage in the boot.

A special note about the STi's security system: it probably needs something special given its attractiveness to thieves, but having a keypad that needs a PIN entered every time you start the car, and an engine that shuts down every time the door is opened, is a major pain.

The other security upgrade is DataDots for foolproof vehicle identification, which is more welcome as it is unobtrusive.

On the right road or, probably more rightly, any race track, the STi offers an exhilarating blend of engine performance, grip and traction that make its $56,000 price seem ludicrously cheap against slower but far dearer sports cars.

But it is difficult to live with in most other situations, being noisy, harsh riding and lacking performance at low engine speeds. The STi is a bargain for dedicated performance buffs, but difficult to justify for anyone after more flexibility and refinement.